The present invention relates to x-ray radiography and, in particular, to the using of radiography plates to record x-ray information.
X-ray radiographs are of great value in diagnosing patient illnesses and monitoring patient status. A variety of x-ray radiographic techniques are now available including, for example, computed tomography (CT) and more conventional x-ray techniques. Radiographs or “radiographic pictures” are commonly taken by way of radiography plates that temporarily or, in some circumstances, permanently record radiographic information. Such radiography plates commonly come in two forms. A first form employs a version of photographic film, which typically is a sheet of translucent supporting material that is coated on one or both of its sides by a photosensitive emulsion. When exposed to photons at the wavelengths of interest, the photosensitive emulsion darkens the film at various locations according to the amounts of exposure that have occurred at any given location.
A second form of radiography plate employs a photo-stimulable phosphor plate. When exposed to x-ray photons from a radiography machine, energy is stored in the sheet at different positions according to the intensity of the radiation exposure at those positions, and thus the sheet stores an image. Then, some time later after the exposure to the high energy radiation, the sheet is “read” by a machine that scans the sheet with a small area beam (e.g., a laser beam) of relatively long-wavelength radiation to release the energy stored in the sheet as light. An appropriate photosensor receives light that is emitted by the sheet and produces electrical signals in accordance with the light received. The electrical energy in turn can be digitized to store the image information for computer access, or to output that image information on a display device or the like.
In each of these cases, although the radiography plates are intended for sensing x-ray photons such as those produced by radiography machines, the plates nevertheless are also sensitive to other light, in that the light would serve to erase the previously stored information. Consequently, to prevent the exposure of the radiography plates to visible light until such time as the radiographic information on those plates can be processed and recorded on a less ephemeral form, the plates typically are housed within boxes or “cassettes” that are impervious to visible light despite allowing for the passage of the high energy radiation produced by the radiographic imaging machines. When a radiograph exposure is taken, the cassette is removed for processing of the plate in the cassette. In the case of traditional photographic film-type radiography plates, the radiographic images are not in a stable form until the film is processed in a conventional manner in a “dark room”. Similarly, in the case of machine-read radiography plates, the cassettes are designed to be inserted into a cassette-reading machine, which is able to remove the radiographic plates from the cassettes and then read the information on those plates.
Although cassette-reading machines are able to “automatically” read the radiographic information stored on machine-read radiography plates, there nevertheless can be considerable delay in the processing of such plates by the cassette-reading machines. Likewise, there can be considerable delay in the processing of photographic film-type radiography plates by film-development equipment. These delays are attributable to the fact that radiography plates are seldom processed, either by cassette-reading machines or by film-development equipment, immediately subsequent to the radiograph exposures. Rather, there tends to be a time gap between the times at which the radiograph exposures occur and the times at which the radiography plates are processed.
A primary reason for this time gap is that radiography machines typically are not physically located proximate the cassette-reading machine or film-development machine at which cassettes are processed. This is due in part to the desirability of using portable radiography machines that can be brought to a patient's location. As a result, when radiographs are taken, the cassettes typically need to be hand-delivered back to the cassette-reading machine or film-development machine for processing, which can take a significant and variable amount of time depending upon the person delivering the cassette. A second reason for the time gap between radiograph exposures and the processing of radiography plates is that radiographic images are often acquired in batches by the technicians who perform the radiographic tests. That is, numerous tests on multiple patients, sometimes situated in different medical units (e.g., Trauma, Intensive Care, Burn, etc.), are often performed by a technician over the course of several hours before a batch of radiographic plates is turned in by the technician for processing.
Despite the existence of these delays, the typical protocol for assigning imaging times to radiography plates indicating the times at which the plates were exposed to x-ray radiation during radiographic procedures is simply to assign the times at which the plates are being processed as the times at which the radiographs were taken. In the case of machine-read radiography plates, in particular, cassette-reading machines typically assign the times at which they process cassettes as the times at which the radiographic information was obtained. Likewise, in the case of photographic film-type radiography plates, typically it is the times at which the plates are processed by film-development equipment that are assigned as the images as the exposure times.
While the times at which radiography plates are processed is often an adequate proxy for the times at which radiographic images were taken, this is not always the case. The existence of these differences between the times at which radiography tests are performed and the times that are assigned to the images resulting from those tests can become particularly disadvantageous in circumstances where a given patient is undergoing relatively rapid changes, or where a given patient is undergoing repeated radiography tests in a relatively short amount of time. In such circumstances, it can become particularly important for physicians and others to understand the exact times at which images have been taken, to understand the rapidity of changes that are occurring in a patient. Further, it is particularly important in such circumstances that the proper order in which different images have been taken be readily apparent to a physician or other personnel reviewing the images. Yet the conventional manner of assigning times to radiography images can make it difficult or impossible for physicians and others to understand the temporal relationships among different radiography images.
Indeed, in some circumstances, the conventional manner of assigning times to radiography images can cause a misinterpretation of the different images and consequently cause a misunderstanding of a patient's condition. For example, if a patient's condition suddenly begins to deteriorate, a STAT film may be requested by a physician and nearly immediately a technician may proceed with performing a radiographic test and have the radiography plates processed. If, prior to the change in the patient's condition, an earlier set of radiographic tests were performed and the processing of the resulting radiography plates has not yet been completed, it is possible that the earlier-obtained radiography images may be assigned later times than the rushed images. A physician reviewing the entire set of processed images, then, may be presented with images that misrepresent the overall progress of a patient's condition.
It therefore would be advantageous if a new radiographic device and/or technique was developed that allowed times to be assigned to radiographic images that more accurately reflected the actual times at which the radiographic tests that produced the images were performed. It further would be advantageous if such a new radiographic device and/or technique could be easily and inexpensively implemented in relation to radiographic images obtained using both film-type and machine-read radiography plates. Further, insofar as conventional radiography plates are relatively expensive devices, it would be advantageous if such a new radiographic device and/or technique could be easily and inexpensively applied to existing radiography plates.